Preparation of ansa metallocene compounds

Abstract

The present invention refers to a process for overcoming the problem of formation of oligomeric-polymeric complexes during preparation of cyclopentadienyl metallocenes comprising ligands bridged by at least three carbon atoms. According to the invention a process is presented comprising the steps of deprotonating a biscyclopentadienyl ligand bridged by a chain having a backbone of at least three carbon atoms by a base and reacting the deprotonated ligand with at least one alkali or alkaline earth metal alkylating agent and a salt of a transition metal belonging to group 3, 4, 5, 6 or to the lanthanide or actinide groups of the Periodic Table of the Elements.

1 . A process for the preparation of ansa metallocenes comprising bridges of a chain having a backbone of at least three carbon atoms, the process comprising:
 deprotonating a biscyclopentadienyl ligand bridged by a chain having a backbone of at least three carbon atoms by a base; and   reacting the deprotonated ligand with at least one alkali or alkaline earth metal alkylating agent and a salt of a transition metal belonging to group 3, 4, 5, 6 or to the lanthanide or actinide groups of the Periodic Table of the Elements.   
     
     
         2 . The process according to  claim 1  comprising:
 (1) deprotonating an alkylene biscyclopentadienyl ligand wherein the ligands are bridged by a chain having a backbone of at least three carbon atoms with 2 molar equivalents of a deprotonating base; 
 (2) adding 2 molar equivalents of an alkylating agent; and 
 (3) adding one molar equivalent of a salt of a transition metal belonging to group 4 of the Periodic Table of the Elements. 
 
     
     
         3 . The process according to  claim 1 , wherein the process is carried out in an aprotic solvent. 
     
     
         4 . The process according to  claim 3 , wherein the aprotic solvent is an aromatic or aliphatic hydrocarbon selected from the group consisting of benzene, toluene, pentane, hexane, heptane and cyclohexane, or is an ether selected from the group consisting of diethylether and tetrahydrofurane. 
     
     
         5 . The process according to  claim 1  wherein the ansa metallocene has the structure of formula I: 
       
         
           
           
               
               
           
         
         wherein 
         M is a transition metal belonging to group 3, 4, 5, 6 or to the lanthanide or actinide groups of the Periodic Table of the Elements (IUPAC version); 
         R B  may be the same or different and are selected from the group consisting of hydrogen, halogen, trimethylsilyl, C 1 -C 10 -alkyl, C 1 -C 10 -fluoroalkyl, C 6 -C 10  fluoroaryl, C 6 -C 10  aryl, C 1 -C 10  alkoxy, C 7 -C 15  alkylaryloxy, C 2 -C 10  alkenyl, C 7 -C 40  arylalkyl, C 8 -C 40  arylalkenyl and C 7 -C 40  alkylaryl; 
         n is an integer between 3 and 20; 
         X are the same or different and are selected from the group consisting of linear or branched, saturated or unsaturated C 1 -C 20  alkyl, C 3 -C 20  cycloalkyl, C 6 -C 20  aryl, C 7 -C 20  alkylaryl and C 7 -C 20  arylalkyl groups, optionally containing one or more Si or Ge atoms; 
         p is an integer from 1 to 3, being equal to the oxidation state of the metal M minus 2; 
         R 11  and R 12  are identical or different and are each hydrogen or a C 1 -C 20  group; and 
         R 13 , R 14 , R 15  and R 16  are identical or different and are each a hydrogen atom or a C 1 -C 20  group, 
         and the alkylene biscyclopentadienyl ligand has the structure of formula (II): 
       
       
         
           
           
               
               
           
         
       
     
     
         6 . The process according to  claim 1 ,
 wherein   M is zirconium;   X are methyl groups;   R B  are hydrogen atoms;   n is 3;   R 12 , R 13  and R 16  are the same and hydrogen;   R 11  is hydrogen or a C 1 -C 8  alkyl and   R 14  and R 15  are the same or different and selected from hydrogen and C 1 -C 8  alkyl, or R 14  and R 15  together with the two carbon atoms of the indenyl form an aromatic or aliphatic C 5  or C 6  ring.   
     
     
         7 . The process according to  claim 1  wherein the salt of the transition metal is used in the form of an ether complex prepared in a hydrocarbon solvent and used directly in the reaction with the ligand salt without separation from the solvent medium. 
     
     
         8 . The process according to  claim 7  wherein the ether complex of the transition metal salt is ZrCl 4 .2 THF in toluene as the solvent. 
     
     
         9 . The process according to  claim 1 , wherein the alkylating agent is methyllithium. 
     
     
         10 . The process of  claim 5  wherein R 11  and R 12  are a C 1 -C 18 -alkyl selected from methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, cyclopentyl or cyclohexyl, isopropyl, isobutyl, isopentyl, isohexyl, tert-butyl, C 2 -C 10 -alkenyl, C 3 -C 15 -alkylalkenyl, C 6 -C 18 -aryl, C 4 -C 18 -heteroaryl, C 7 -C 20 -arylalkyl, C 7 -C 20 -alkylaryl, fluorinated C 1 -C 12 -alkyl, fluorinated C 6 -C 18 -aryl, fluorinated C 7 -C 20 -arylalkyl or fluorinated C 7 -C 20 -alkylaryl, where R 11  together with R 12  may also form a monocyclic or polycyclic ring system. 
     
     
         11 . The process of  claim 5  wherein R 13 , R 14 , R 15 , and R 16 , are selected from methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, cyclopentyl or cyclohexyl, isopropyl, isobutyl, isopentyl, isohexyl, tert-butyl, C 2 -C 10 -alkenyl, C 3 -C 15 -alkylalkenyl, C 6 -C 18 -aryl, C 4 -C 18 -heteroaryl, C 7 -C 20 -arylalkyl, C 7 -C 20 -alkylaryl, fluorinated C 1 -C 12 -alkyl, fluorinated C 6 -C 18 -aryl, fluorinated C 7 -C 20 -arylalkyl or fluorinated C 7 -C 20 -alkylaryl and two adjacent radicals R 13  and R 14  or R 14  and R 15  or R 15  and R 16  may form together with the two carbon atoms of the indenyl ring a monocyclic or bi- or polycyclic ring system. 
     
     
         12 . The process of  claim 11  wherein the monocyclic or bi- or polycyclic ring system is selected from an aromatic or aliphatic cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl or cyclodecyl.